1. Field of the Invention
The present invention relates to a vacuum envelope and an electron emission display having the vacuum envelope, and more particularly, to a vacuum envelope having a sealing structure and an electron emission display having the vacuum envelope.
2. Description of Related Art
In general, electron emission elements can be classified into those using hot cathodes as an electron emission source and those using cold cathodes as an electron emission source.
There are several types of cold cathode electron emission elements, including Field Emitter Array (FEA) elements, Surface Conduction Emitter (SCE) elements, Metal-Insulator-Metal (MIM) elements, and Metal-Insulator-Semiconductor (MIS) elements.
Electron emission elements are arrayed (or arranged) on a first substrate to form an electron emission device. The electron emission device is combined with a second substrate, on which a light emission unit having phosphor layers and an anode electrode is arranged, to make an electron emission display.
That is, a conventional electron emission device includes electron emission regions and a plurality of driving electrodes functioning as scan and data electrodes. By operating the electron emission regions and the driving electrodes, an on/off operation of each pixel and an amount of electron emission are controlled. A conventional electron emission display excites phosphor layers using electrons emitted from the electron emission regions to display a certain (or predetermined) image.
The electron emission display includes an electron emission unit and a light emission unit that are arranged in a vacuum envelope (or chamber). In order to allow the electron emission unit to effectively operate, it is essential to maintain an airtightness of the vacuum envelope.
The vacuum envelope includes a first substrate and a second substrate facing the first substrate, the first substrate and the second substrate being spaced apart from each other. A glass frame is arranged between the first substrate and the second substrate. The glass frame is adhered to the first substrate and the second substrate by frit.
The glass frame includes a plurality of sections that are adhered to each other by frit. When the sections of the glass frame have different lengths, the sections also have different levels of thermal expansivity. Therefore, the sections contract or expand during a firing process, and thus a shape or shapes of the first substrate and/or the second substrate may be distorted and/or the sections of the glass frame may move away from desired positions. This causes the airtightness of the vacuum envelope to be deteriorated.